Time-dependent escape of cosmic rays from supernova remnants, and their interaction with dense media

Telezhinsky, I.; Dwarkadas, Vikram V.; Pohl, M.

doi:10.1051/0004-6361/201118639

Cited by 42 publications

(43 citation statements)

References 53 publications

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“…At a given location, this leads to very hard particle spectra with cutoff at an energy determined by the distance from the shock, the diffusion coefficient, and the shock velocity (Gabici et al 2009;Ellison & Bykov 2011;Telezhinsky et al 2012b). It has been argued before that the escape of cosmic rays from SNRs might lead to strong TeV-band γ-ray emission from molecular clouds located 10 pc or more from the remnant.…”

Section: Hadronic Emission From the Cosmic-ray Precursormentioning

confidence: 99%

Analysis of GeV-bandγ-ray emission from supernova remnant RX J1713.7-3946

Federici¹,

Pohl

Telezhinsky

et al. 2015

A&A

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Context. RX J1713.7-3946 is the brightest shell-type supernova remnant (SNR) of the TeV γ-ray sky. Earlier Fermi-LAT results on low energy γ-ray emission suggested that, despite large uncertainties in the background determination, the spectrum is inconsistent with a hadronic origin. Aims. We update the GeV-band spectra using improved estimates for the diffuse Galactic γ-ray emission and more than double the volume of data. We further investigate the viability of hadronic emission models for RX J1713.7-3946. Methods. We produced a high-resolution map of the diffuse Galactic γ-ray background corrected for the HI self-absorption and used it in the analysis of more than five years worth of Fermi-LAT data. We used hydrodynamic scaling relations and a kinetic transport equation to calculate the acceleration and propagation of cosmic rays in SNR. We then determined spectra of hadronic γ-ray emission from RX J1713.7-3946, separately for the SNR interior and the cosmic-ray precursor region of the forward shock, and computed flux variations that would allow us to test the model with observations. Results. We find that RX J1713.7-3946 is now detected by Fermi-LAT with very high statistical significance, and the source morphology is best described by that seen in the TeV band. The measured spectrum of RX J1713.7-3946 is hard with index γ = 1.53 ± 0.07, and the integral flux above 500 MeV is F = (5.5 ± 1.1) × 10 −9 photons cm −2 s −1 . We demonstrate that scenarios based on hadronic emission from the cosmic-ray precursor region are acceptable for RX J1713.7-3946, and we predict a secular flux increase at a few hundred GeV at the level of around 15% over ten years, which may be detectable with the upcoming Cherenkov Telescope Array (CTA) observatory.

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Section: Hadronic Emission From the Cosmic-ray Precursormentioning

confidence: 99%

Analysis of GeV-bandγ-ray emission from supernova remnant RX J1713.7-3946

Federici¹,

Pohl

Telezhinsky

et al. 2015

A&A

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“…To model cosmic ray acceleration we use a kinetic approach in test-particle approximation [9,10,11]. We numerically solve the time-dependent transport equation for the differential number density of cosmic rays in spherically-symmetric geometry [12]:…”

Section: Particle Accelerationmentioning

confidence: 99%

Transport of magnetic turbulence in supernova remnants

Brose¹,

Telezhinsky²,

Pohl³

2016

Proceedings of the 34th International Cosmic Ray Conference — PoS(ICRC2015)

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Supernova remnants are known as sources of galactic cosmic rays for their non-thermal emission of radio waves, X-rays, and gamma-rays. However, the observed soft broken power-law spectra are hard to reproduce within standard acceleration theory based on the assumption of Bohm diffusion. Here we model cosmic ray acceleration in a time-dependent and self-consistent way by simultaneous solving the coupled transport equations for cosmic rays and isotropic scattering turbulence. The transport equation for cosmic ray is solved in a test-particle approach while the equation for scattering turbulence considers just Alfven waves. Their spectral energy density determines the spatial diffusion coefficient of cosmic rays. Our co-moving expanding grid extends upstream to several shock radii, so we are able to self-consistently study the escape of CRs from their acceleration site. We demonstrate that the system is typically not in a steady state. In fact, even after several thousand years of evolution, no equilibrium situation is reached. The resulting time-dependent particle spectra obtained in this work strongly differ from those derived assuming a steady state and Bohm diffusion. Our results indicate that the proper account for the evolution of scattering turbulence and hence particle diffusion coefficient is crucial for the formation of the observed soft spectra and spectral breaks.

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“…At a given location, this leads to very hard particle spectra with cut off at an energy determined by the distance from the shock, the diffusion coefficient, and the shock velocity (Gabici et al 2009;Ellison & Bykov 2011;Telezhinsky et al 2012b). It has been argued before that the escape of cosmic rays from SNRs might lead to strong TeV-band γ-ray emission from molecular clouds located 10 pc or more from the remnant.…”

Section: Hadronic Emission From the Cosmic-ray Precursormentioning

confidence: 99%

Analysis of GeV-band gamma-ray emission from SNR RX J1713.7-3946

Brose¹,

Federici²,

Pohl³

et al. 2016

Proceedings of the 34th International Cosmic Ray Conference — PoS(ICRC2015)

View full text Add to dashboard Cite

Context. RX J1713.7-3946 is the brightest shell-type Supernova remnant (SNR) of the TeV γ-ray sky. Earlier Fermi-LAT results on low-energy γ-ray emission suggested that, despite large uncertainties in the background determination, the spectrum is inconsistent with a hadronic origin. Aims. We update the GeV-band spectra using improved estimates for the diffuse galactic γ-ray emission and more than doubled data volume. We further investigate the viability of hadronic emission models for RX J1713.7-3946. Methods. We produced a high-resolution map of the diffuse Galactic γ-ray background corrected for the HI self-absorption and used it in the analysis of more than 5 years worth of Fermi-LAT data. We used hydrodynamic scaling relations and a kinetic transport equation to calculate the acceleration and propagation of cosmic-rays in SNR. We then determined spectra of hadronic γ-ray emission from RX J1713.7-3946, separately for the SNR interior and the cosmic-ray precursor region of the forward shock, and computed flux variations that would allow to test the model with observations. Results. We find that RX J1713.7-3946 is now detected by Fermi-LAT with very high statistical significance, and the source morphology is best described by that seen in the TeV band. The measured spectrum of RX J1713.7-3946 is hard with index γ = 1.53 ± 0.07, and the integral flux above 500 MeV is F = (5.5 ± 1.1) × 10 −9 photons cm −2 s −1 . We demonstrate that scenarios based on hadronic emission from the cosmic-ray precursor region are acceptable for RX J1713.7-3946, and we predict a secular flux increase at a few hundred GeV at the level of around 15% over 10 years, which may be detectable with the upcoming CTA observatory.

show abstract

Time-dependent escape of cosmic rays from supernova remnants, and their interaction with dense media

Cited by 42 publications

References 53 publications

Analysis of GeV-bandγ-ray emission from supernova remnant RX J1713.7-3946

Analysis of GeV-bandγ-ray emission from supernova remnant RX J1713.7-3946

Transport of magnetic turbulence in supernova remnants

Analysis of GeV-band gamma-ray emission from SNR RX J1713.7-3946

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